1. Field of the Invention
The invention relates to an image capturing device and, more particularly, to an image capturing device with auto-focus function and an auto-focus method.
2. Description of the Prior Art
As digital camera module is getting more and more popular, so far most of electronic devices, such as cell phones, flat computers, personal digital assistants, etc., are equipped with a digital camera module. Furthermore, the resolution of the digital camera module is increasing continuously. However, the resolution of a display panel is limited due to current technology such that the display panel cannot render image information captured by the digital camera module completely. For example, the maximum resolution of a display panel on a cell phone is only about 1280*720 (i.e. 1M) but the resolution of a digital camera module has achieved about 3264*2448 (i.e. 8M). Since the resolution of the display panel is smaller than that of the digital camera module, a user cannot determine whether a focus frame displayed by the display panel has caught correct focus by his or her eyes. In other words, the user cannot know whether an image is defined while focusing or taking the image. To ensure the definition of the image, the user has to open and zoom in parts of the stored image or use zoom in/out function while taking the image. However, the aforesaid manners are inconvenient and waste time.